The use of noise dampening material in combination with a brake friction material and a metallic support element is well-known as disclosed by U.S. Pat. No. 4,240,530 issued in the name of Tillenburg. Such patent teaches a disc brake friction pad assembly comprised of a multi-part metallic carrier plate and a friction material cure-bonded to one face of the carrier plate. The carrier plate part joined to the friction material is bonded to another similarly-configured carrier plate part by a cured rubber-asbestos dampening material. Another publication, Japanese Patent No. 62-106132 issued in the name of Kani to Toyota, discloses the same type of brake friction pad assembly in which the carrier plate parts are preferably made of a bainite cast iron material. The elasticity (dampening material) layer which joins the carrier plate parts together is unspecified by the Japanese publication.
U.S. Pat. No. 3,966,026 issued in the name of Filderman teaches a braking member construction in which a noise reduction capability is obtained through use of a friction material support that is comprised of a stack of thin metallic sheets or strips, contiguous to each other over their whole surface and all assembled together by gluing, welding in zones, riveting, insetting in a rim or flange, or the like. The nature of the glue is not specified. See also U.S. Pat. No. 4,064,975 issued in the name of the same Filderman for another disclosure of the braking member construction.
U.S. Pat. No. 4,022,302 issued in the name of Janssen teaches that brake noise reduction may be achieved by coating the exterior surface of the brake support plate with a thin layer of vulcanized latex.
A further teaching of a disc brake pad assembly utilizing a noise dampening material in combination with a metallic support plate (brake shoe) and a friction material is U.S. Pat. No. 4,373,615 issued in the name of Melinat. In the Melinat assembly a semi-metallic friction material is secured to a multi-part metallic brake shoe comprised of bonded metallic, ceramic, and elastomeric (rubber) layers.
U.S. Pat. No. 5,083,643 issued in the name of Hummel et al. and assigned to the assignee of this application, discloses the use of a noise dampening material in the construction of a drum brake friction block and shoe assembly. Such dampening material is essentially an elastomer and is formed into separate segments that are positioned in correspondingly configured grooves located in the friction material block.
For a teaching of the use of an elastomeric sound dampening material in a railway disc brake see Germany Patent No. DE 3734289-A. For a teaching of the use of a flexible graphite sheet layer in a disc brake pad assembly which appears to function more as a heat barrier rather than a noise reduction device see Japan Patent No. 59-9326(A) issued in the name of Maruya and assigned to Nissan.